TRaining an adult dog?

So, I have a show english springer spaniel, she is called Ivy. She is about a year and a 1/4 years old. She's lovely and very affectionate and cuddely. HOWEVER! she is sooo badly trained. She does;
sit
paw
stay (in sit)
and heels (most of the time)
But we really need her to lie down on command, come to you all of the time not just a few times and importantly Get over her seperation anxiety, it is irriatating. We can never leave her alone- she howls the house down. when we need to go shopping she howls the car down or howls outside the shop. when we went on holiday and left her with a dog boarder person (not a kennel- 1 to 1 type thing) Ivy just howled cuz she missed us.
Pleassee help us if you can
Flo

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Answers

Enroll her in a dog training class.
Have you tried properly crate training her (making it a wonderful safe place)and desensitizing her to your absences? If all else fails you could hire a behaviorist for the separation anxiety.